The present invention relates to an organic conductive complex, more particularly, to an organic conductive complex that is advantageously used for a thermal switch, a thermoelectric elemental device, a galvanic cell, a diode switch, a thermoelectric and electrothermal modulation device, etc., and has the potential to be used in such applications as superconducting materials, third-order nonlinear materials and photoconductive materials.
Synthetic metals that have been proposed as metal substitutes include not only conductive polymers and graphite compounds but also organic conductive complexes (e.g. ion radical salts and intermolecular charge-transfer complexes) that are composed of electron donors and acceptors. In organic conductive complexes, electrons are transferred from the electron donor to the acceptor and are stabilized to form a stable complex; the resulting high intramolecular and intermolecular mobility of electrons (i.e. delocalization) contributes to conducting or semiconducting electric behavior.
Electron donors that are capable of forming organic complexes having high conductivity may be exemplified by bisethylenedithia-tetrathiafulvalene (BEDTTTF) (as described, e.g., in Chem. Lett., 1985, pp. 1293 and Pis'ma Zh. Eksp. Teor. Fiz., vol. 40, pp. 387 (1984)) and tetrathiafulvalene (TTF) (as described, e.g., in Phys. Rev., vol. B13, pp. 5105 (1976) and Phys. Soc. Japan, vol. 41, pp. 351 (1976)). Illustrative electron acceptors include 7,7,8,8-tetracyanoquinodimethane (TCNQ) tetracyanoethylene (TCNE). All of these compounds have planar molecular structures and it is theorized that within the crystal of an organic conductive complex, their planes are alternately stacked, with adjacent planes facing substantially parallel to each other, so that .pi. electrons in the electron donor will be transferred to the .pi. orbital in the electron acceptor, thereby creating the "delocalized state" mentioned above.
While various compounds are used as dyes, anthraquinone derivatives have substantially planar molecular structures of the same type as those possessed by the electron donors and acceptors described above. The present inventors thus theorized that by selecting proper substituents, anthraquinone derivatives useful as electron donors or acceptors in the synthesis of organic conductive complexes might be obtained and on the basis of this assumption, they reviewed various anthraquinone derivatives to search for the compounds that would be as effective as BEDT-TTF, TTF, TCNQ, TCNE, etc. As a result, the present inventors found that an anthraquinone derivative having an electron donating group on the 1, 4, 5 and 8 positions of 9, 10-anthraquinone would be useful as an electron donor in an organic conductive complex.